It puts electronic monitors in boxes of parts as they travel between plants in China to make sure they don't get leaked.

The finished iPad 2 shipped in unmarked boxes that were monitored at every handoff point by Apple employees.

Many suppliers are required to have two weeks' worth of inventory within a mile of Apple's Chinese assembly plants.

Apple offered one parts manufacturer an up-front payment of $1 billion to commit most of a factory to Apple products. The manufacturer said no because it didn't want to be too dependent.

Designer Jony Ive wanted the MacBook Air to have a green light appear to be shining THROUGH the case when the camera was on. The only way to do this was by poking tiny holes in the aluminum with a laser -- so Apple found a supplier for the laser machines and convinced it to sign an exclusive. It's since bought hundreds of the machines at about $250,000 apiece.

Apple can get away with all this because it buys parts in huge volumes.

It also helps that Apple has more than $80 billion in cash, and isn't afraid to use it to improve its supply chain efficiency -- next year, the company plans to double its spending on supply chain to $7.1 billion.

Apple's hyper-efficient supply chain was largely oveseen by Tim Cook, who won enough trust from Steve Jobs to win the CEO role when Jobs stepped down.